1. Field of the Invention
Exemplary embodiments of the invention relate to reinforcement systems. More particularly, embodiments relate to apparatus, assemblies, and systems used to provide composite reinforcement by utilizing multiple different reinforcement mechanisms. More particularly still, embodiments relate to coupling a reinforcement rod to a reinforcement sheet to provide reinforcement of one or more structures, such that both the reinforcement rod and reinforcement sheet collectively provide reinforcement with reduced stress concentrations adversely affecting structural integrity and/or performance.
2. The Relevant Technology
Fibre-reinforced polymer (FRP) composite rods and fabric have emerged as alternatives to traditional construction, rehabilitation, and repair systems of reinforced concrete columns, bridges, girders, and the like. Relative to traditional reinforcement materials such as steel, FRP provides a relatively high strength-to-weight ratio, a resistance to corrosion, and low labor cost as a result of its relative ease of use and application. Such benefits have been significant factors in the use of FRP in a large number of public and private projects, and the same benefits also create expectations that deployment of FRP will escalate, particularly in regions that are seismically active.
FRP materials are also becoming increasingly available such that they can be used in a wider range of applications. FRP rods, for example, are being used to reinforce girders and beams in bridges, buildings, and other structures. For instance, an FRP rod may be attached to an anchor that is in turn secured to the girder or beam. Alternatively, near-surface mount (NSM) techniques may be employed. To utilize NSM techniques, a groove is traditionally cut into a concrete or masonry surface. The FRP rod may then be placed within the groove and secured in place using an epoxy adhesive or cementitious grout, to effectively embed the FRP rod inside the concrete or masonry.
FRP fabrics have also more recently been used to reinforce, rehabilitate, and/or repair existing beams, columns, plates, and other structures. More particularly, FRP fabrics have been utilized in a manner that provides wholly external application of the FRP to the structure. FRP fabric may, for example, be wrapped around an external surface of a beam and bonded in place to repair structures that have undergone some seismic or other damage, or to strengthen a beam or joint, so as to prevent failure of the structure.
Relative to other reinforcement, repair, and rehabilitation materials, FRP materials still carry with them a relatively high cost. As a result, there is a desire to minimize the amount of FRP materials in use, so that the associated costs may also be reduced. Consequently, no one-size-fits-all approach is always desired, and some structures may benefit from use of FRP reinforcement rods, while FRP reinforcement fabric may provide greater benefits for other structures. In still other structures or applications, a composite approach that utilizes both FRP rods and FRP fabric may be desired.
Unfortunately, no single mechanism currently allows effective use of FRP rods and FRP fabric in a manner that structurally links the fabric to the reinforcement rods. More particularly, no adaptor has been developed to allow a transition from a rod reinforcement member to a sheet reinforcement member. Further, while possible to wrap the FRP sheet materials directly around the FRP rods, such a procedure would cause the sheet materials to bend and deform. Then, as a load is applied, the deformed sheet materials would have localized stress concentrations that reduce the structural integrity of the FRP sheet materials, thereby reducing their load carrying capabilities. Such a design may therefore be prone to premature failure, or may require additional materials to be utilized, thereby increasing the cost for the repair or rehabilitation of the structure.
Accordingly, what is desired are adaptors and attachment apparatus and systems that are usable with FRP materials, and which can couple a rod to a sheet material in a manner that reduces the localized stress concentrations, thereby also reducing the likelihood of premature failure of the sheet materials. Preferably, such adaptors, apparatus, and systems are adaptable to a wide variety of different materials and applications.